Methods of Inducing Melanogenesis in a Subject

ABSTRACT

Described herein are methods and compositions for inducing melanogenesis in a human subject. The method comprises administering to a subject an alpha-MSH analogue, in an effective amount and time to induce melanogenesis by the melanocytes in epidermal tissue of subject without inducing homologous desensitization of the melanocortin-1 receptors.

BACKGROUND

The melanocortins include a family of peptide hormones that inducepigmentation by interaction with melanocortin-1 receptors (MC1R) in theepidermis.¹ The primary pigmentary hormone that is released from thepars intermedia of the pituitary gland in some non-human animals, andfrom UV exposed keratinocytes in human skin, is alpha melanocytestimulating hormone (alpha-MSH).¹ This 13 amino acid peptide binds toMC1R to induce cyclic AMP-mediated signal transduction, which leads tothe synthesis of melanin polymers from DOPA precursors.¹ Two types ofmelanins can be expressed in humans. The brownish-black pigmenteumelanin is believed to convey protection from sun damage, whereas thereddish, sulfur-containing pigment, pheomelanin, is often expressed inlight-skinned human populations that report a poor tanning response tosunlight.² These poorly-tanning, easily-burning populations oftenpossess defects in the MC1R gene³ and are generally thought to be at agreater risk of developing both melanoma and non-melanoma skincancers.^(4,5)

It has previously been disclosed that a super-potent derivative ofalpha-MSH, Melanotan (Nle⁴-D-Phe⁷-alpha MSH, also referred to herein as“Melanotan-1” or “MT1”), can induce tanning in human volunteers.⁶Melanotan contains two amino acid substitutions and is approximately 100to 1,000-fold more potent than the native hormone at inducingpigmentation in experimental systems such as the frog skin bioassay orin cultured human keratinocytes.⁷ In humans, Melanotan primarily induceseumelanin synthesis in the skin in concert with its tanning effect.⁸Although melanotropins have been postulated to affect immunologicchanges, ^(9,10,11) all of the prior trials reported only minimal sideeffects such as facial flushing and transient GI upset, unless dosesgreater than those needed for tanning were administered.¹²

There is compelling evidence that melanotropic peptides may provide apotential for increasing melanin pigmentation of human skin. SyntheticMSH may be used to enhance skin pigmentation of normal or light-skinnedindividuals to protect them from the hazards of solar radiation. Severalstudies have suggested that individuals whose skin tends to burn easilyon exposure to the sun and does not tan readily are at higher risk ofboth nonmelanoma skin tumors and of cutaneous melanoma.^(16,17,18) Thereis unambiguous evidence that UV radiation is responsible for skin cancerin humans. In the face of increased deterioration of the ozone layer andthe increasing incidence of and mortality from skin cancer, the abilityto stimulate the skin's own “protective mechanism” of tanning may proveextremely important as photoprotective strategy.

Accordingly, described herein are methods for inducing melanogenesis ina human subject by administering alpha-MSH analogues to the subject atgreatly reduced plasma levels, which surprisingly leads to increasedmelanin density levels in the subject. By increasing melanin levels in asubject, it is possible to reduce or prevent the occurrence of UVradiation-induced skin damage in the subject. Additionally, the reducedamount of alpha-MSH analogue that is required in the methods describedherein avoids undesirable side effects associated with higher doses.

SUMMARY

Described herein are methods for inducing melanogenesis in a subject.The advantages of the invention will be set forth in part in thedescription which follows, and in part will be obvious from thedescription, or may be learned by practice of the aspects describedbelow. The advantages described below will be realized and attained bymeans of the elements and combinations particularly pointed out in theappended claims. It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory only and are not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several aspects described below.Like numbers represent the same elements throughout the figures.

FIG. 1 shows the in vitro release of Melanotan from implants treatedwith ethyl acetate.

FIG. 2 shows the in vitro release of Melanotan from implant formulationsmade from 85:15 poly-(D,L-lactide-co-glycolide) copolymers.

FIG. 3 shows the in vitro release of Melanotan from implant formulationsmade from 84:16 poly-(D,L-lactide-co-glycolide) copolymers.

FIG. 4 shows the pharmacokinetic data from Study 1 described herein.

FIG. 5 shows the pharmacokinetic data from Study 3 described herein.

FIG. 6 shows the pharmacokinetic data from Study 4 described herein.

FIG. 7 shows the comparison of melanin density change (MD %) in thesubjects in Studies 1, 2, 3 and 4 described herein.

DETAILED DESCRIPTION

Before the present compounds, compositions, and/or methods are disclosedand described, it is to be understood that the aspects described beloware not limited to specific compounds, synthetic methods, or uses assuch may, of course, vary. It is also to be understood that theterminology used herein is for the purpose of describing particularaspects only and is not intended to be limiting.

In this specification and in the claims that follow, reference will bemade to a number of terms that shall be defined to have the followingmeanings:

Throughout this specification, unless the context requires otherwise,the word “comprise,” or variations such as “comprises” or “comprising,”will be understood to imply the inclusion of a stated integer or step orgroup of integers or steps but not the exclusion of any other integer orstep or group of integers or steps.

It must be noted that, as used in the specification and the appendedclaims, the singular forms “a,” “an” and “the” include plural referentsunless the context clearly dictates otherwise. Thus, for example,reference to “a pharmaceutical carrier” includes mixtures of two or moresuch carriers, and the like.

“Optional” or “optionally” means that the subsequently described eventor circumstance can or cannot occur, and that the description includesinstances where the event or circumstance occurs and instances where itdoes not.

Ranges may be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another aspect includes from the one particular value and/orto the other particular value. Similarly, when values are expressed asapproximations, by use of the antecedent “about,” it will be understoodthat the particular value forms another aspect. It will be furtherunderstood that the endpoints of each of the ranges are significant bothin relation to the other endpoint, and independently of the otherendpoint.

References in the specification and concluding claims to parts byweight, of a particular element or component in a composition orarticle, denotes the weight relationship between the element orcomponent and any other elements or components in the composition orarticle for which a part by weight is expressed. Thus, in a compoundcontaining 2 parts by weight of component X and 5 parts by weightcomponent Y, X and Y are present at a weight ratio of 2:5, and arepresent in such ratio regardless of whether additional components arecontained in the compound.

A weight percent of a component, unless specifically stated to thecontrary, is based on the total weight of the formulation or compositionin which the component is included.

By “contacting” is meant an instance of exposure by close physicalcontact of at least one substance to another substance. For example,contacting can include contacting a substance, such as a pharmacologicagent, with a cell. A cell can be contacted with a test compound, forexample, an alpha-MSH analogue, by adding the agent to the culturemedium (by continuous infusion, by bolus delivery, or by changing themedium to a medium that contains the agent) or by adding the agent tothe extracellular fluid in vivo (by local delivery, systemic delivery,intravenous injection, bolus delivery, or continuous infusion). Theduration of contact with a cell or group of cells is determined by thetime the test compound is present at physiologically effective levels orat presumed physiologically effective levels in the medium orextracellular fluid bathing the cell.

By “prevent” or “preventing” means the administration of a compositionto a subject or a system at risk for an undesirable condition. Thecondition can include a disease or a predisposition to a disease.Prevention can range from a reduction in the severity of the conditionto the complete ablation of the condition.

By “effective amount and time” means a therapeutic amount and timeneeded to achieve the desired result or results, e.g., inducingmelanogenesis in a subject.

By “induce” means initiating a desired response or result that was notpresent prior to the induction step. The term “induce” also includes theterm “potentiate.”

The term “potentiate” means sustaining a desired response at the samelevel prior to the potentiating step or increasing the desired responseover a period of time.

The term “melanogenesis” as referred to herein is defined as the abilityof a subject to produce melanins by melanin-producing cells, ormelanocytes.

The term “homologous desensitization” as referred to herein is definedas the inhibition of a cellular response upon continuous exposure to anagonist.

The term “epidermal tissue” as referred to herein includes in particularthe skin of a subject.

Disclosed are compounds, compositions, and components that can be usedfor, can be used in conjunction with, can be used in preparation for, orare products of the disclosed methods and compositions. These and othermaterials are disclosed herein, and it is understood that whencombinations, subsets, interactions, groups, etc. of these materials aredisclosed that while specific reference of each various individual andcollective combinations and permutation of these compounds may not beexplicitly disclosed, each is specifically contemplated and describedherein. For example, if a number of different alpha-MSH analogues andbiodegradable polymers are disclosed and discussed, each and everycombination and permutation of the alpha-MSH analogue and biodegradablepolymer are specifically contemplated unless specifically indicated tothe contrary. Thus, if a class of molecules A, B, and C are disclosed aswell as a class of molecules D, E, and F and an example of a combinationmolecule, A-D is disclosed, then even if each is not individuallyrecited, each is individually and collectively contemplated. Thus, inthis example, each of the combinations A-E, A-F, B-D, B-E, B-F, C-D,C-E, and C-F are specifically contemplated and should be considereddisclosed from disclosure of A, B, and C; D, E, and F; and the examplecombination A-D. Likewise, any subset or combination of these is alsospecifically contemplated and disclosed. Thus, for example, thesub-group of A-E, B-F, and C-E are specifically contemplated and shouldbe considered disclosed from disclosure of A, B, and C; D, E, and F; andthe example combination A-D. This concept applies to all aspects of thisdisclosure including, but not limited to, steps in methods of making andusing the disclosed compositions. Thus, if there are a variety ofadditional steps that can be performed it is understood that each ofthese additional steps can be performed with any specific embodiment orcombination of embodiments of the disclosed methods, and that each suchcombination is specifically contemplated and should be considereddisclosed.

Described herein are methods for inducing melanogenesis in a humansubject. The methods herein increase melanin production without inducinghomologous desensitization of the melanocortin-1-receptors of thesubject. This is accomplished by administering alpha-MSH analogues tothe subject so that low concentrations of the alpha-MSH analogue arepresent in the plasma of the subject. In general, higher doses ofalpha-MSH analogue are required to increase melanin production in asubject. However, undesirable side effects can occur when high doses ofalpha-MSH analogue are administered. By increasing melanin production ina subject, it is possible to prevent the occurrence of UVradiation-induced skin damage in a subject that would normally besusceptible to such damage.

In one aspect, the method for inducing melanogenesis in a human subjectcomprises administering to the subject an alpha-MSH analogue in aneffective amount and time to induce melanogenesis by the melanocytes inepidermal tissue of the subject without inducing homologousdesensitization of the melanocortin-1 receptors of the subject.

In another aspect, described herein are methods for inducingmelanogenesis in a human subject, comprising administering to thesubject an effective amount of an alpha-MSH analogue to inducemelanogenesis by the melanocytes in epidermal tissue of the subject,wherein the alpha-MSH analogue is administered at a level not exceeding10 ng/ml in the plasma of the subject for a period of at least 24 hours.

In yet another aspect, the invention provides a composition for inducingmelanogenesis in a human subject, wherein the composition administers analpha-MSH analogue to the subject in an effective amount and time toinduce melanogenesis by the melanocytes in epidermal tissue of thesubject without inducing homologous densitization of the melanocortin-1receptors of the subject.

In this aspect, the invention also provides a composition for inducingmelanogenesis in a human subject, wherein the composition administers analpha-MSH analogue to the subject at a level not exceeding 10 ng/ml inthe plasma of the subject for a period of at least 24 hours.

The term “alpha-MSH analogue” referred to herein is defined as aderivative of alpha-MSH which exhibits agonist activity for themelanocortin-1 receptor (MC1R), the receptor to which alpha-MSH binds toinitiate the production of melanin within a melanocyte. Such derivativesinclude derivatives in which (i) one or more amino acid residues aredeleted from the native alpha-MSH molecule at the N-terminal end, theC-terminal end, or both; and/or (ii) one or more amino acid residues ofthe native alpha-MSH molecule are replaced by another natural,non-natural or synthetic amino acid residue; and/or (iii) anintramolecular interaction forms as a cyclic derivative.

The use of any alpha-MSH analogue is contemplated in the methodsdescribed herein. Several derivatives of α-MSH have been synthesized.¹⁹In one aspect, the alpha-MSH analogues described in U.S. Pat. Nos.4,457,864, 4,485,039, 4,866,038, 4,918,055, 5,049,547, 5,674,839 and5,714,576 and Australian Patents Nos. 597630 and 618733, which areherein incorporated by reference for their teachings with respect toalpha-MSH analogues and their synthesis thereof, can be used herein.

In one aspect, the alpha-MSH analogue may be a compound as disclosed inAustralian Patent No. 597630, selected from:

(a) compounds of the formula:

Ac-Ser-Tyr-Ser-M-Gln-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH₂

wherein M is Met, Nle or Lys; and(b) compounds of the formula:

R₁-W-X-Y-Z-R₂

wherein

R₁ is Ac-Gly-, Ac-Met-Glu, Ac-Nle-Glu-, or Ac-Tyr-Glu-;

W is -His- or -D-His-;

X is -Phe-, -D-Phe-, -Tyr-, -D-Tyr-, or -(pNO₂)D-Phe⁷-;

Y is -Arg- or -D-Arg-;

Z is -Trp- or -D-Trp-; and

R₂ is —NH₂; -Gly-NH₂; or -Gly-Lys-NH₂.

In another aspect, the alpha-MSH analogue may be selected from cyclicanalogues which are disclosed in Australian Patent No. 618733 where anintramolecular interaction (such as a disulfide or other covalent bond)exists (1) between the amino acid residue at position 4 and an aminoacid residue at position 10 or 11, and/or (2) between the amino acidresidue at position 5 and the amino acid residue at position 10 or 11.

The alpha-MSH analogue may be a linear analogue as disclosed in U.S.Pat. No. 5,674,839, selected from the group consisting of:

Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Lys-Gly-Pro-Val-NH₂

Ac-Ser-Tyr-Ser-Nle-Asp-His-D-Phe-Arg-Trp-Lys-Gly-Pro-Val-NH₂

-   -   Ac-Nle-Glu-His-D-Phe-Arg-Trp-Lys-Gly-Pro-Val-NH₂    -   Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-Gly-Pro-Val-NH₂    -   Ac-Nle-Asp-His-D-Phe-Arg-Trp-Gly-NH₂    -   Ac-Nle-Glu-His-D-Phe-Arg-Trp-Lys-NH₂    -   Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH₂    -   Ac-Nle-Glu-His-D-Phe-Arg-Trp-Orn-NH₂    -   Ac-Nle-Asp-His-D-Phe-Arg-Trp-Orn-NH₂    -   Ac-Nle-Glu-His-D-Phe-Arg-Trp-Dab-NH₂    -   Ac-Nle-Asp-His-D-Phe-Arg-Trp-Dab-NH₂    -   Ac-Nle-Glu-His-D-Phe-Arg-Trp-Dpr-NH₂    -   Ac-Nle-Glu-His-Phe-Arg-Trp-Lys-NH₂    -   Ac-Nle-Asp-His-Phe-Arg-Trp-Lys-NH₂

The alpha-MSH analogue may also be a cyclic analogue as disclosed inU.S. Pat. No. 5,674,839, selected from the group consisting of:

Where referred to herein, Ala=alanine, Arg=arginine,Dab=2,4-diaminobutyric acid, Dpr=2,3-diaminopropionic acid, Glu=glutamicacid, Gly=glycine, His=histidine, Lys=lysine, Met=methionine,Nle=norleucine, Orn=ornithine, Phe=phenylalanine,(pNO₂)Phe=paranitrophenylalanine, Plg=phenylglycine, Pro=proline,Ser=serine, Trp=tryptophan, TrpFor=N¹⁻ formyl-tryptophan, Tyr=tyrosine,Val=valine. All peptides are written with the acyl-terminal end at theleft and the amino terminal end to the right; the prefix “D” before anamino acid designates the D-isomer configuration, and unlessspecifically designated otherwise, all amino acids are in the L-isomerconfiguration.

In one aspect, the alpha-MSH analogue can be

[D-Phe⁷]-alpha-MSH,

[Nle⁴, D-Phe⁷]-alpha-MSH,

[D-Ser¹, D-Phe⁷]-alpha-MSH,

[D-Tyr², D-Phe⁷]-alpha-MSH,

[D-Ser³, D-Phe⁷]-alpha-MSH,

[D-Met⁴, D-Phe⁷]-alpha-MSH,

[D-Glu⁵, D-Phe⁷]-alpha-MSH,

[D-His⁶, D-Phe⁷]-alpha-MSH,

[D-Phe⁷, D-Arg⁸]-alpha-MSH,

[D-Phe⁷, D-Trp⁹]-alpha-MSH,

[D-Phe⁷, D-Lys¹¹]-alpha-MSH,

[D-Phe⁷, D-Pro¹²]-alpha-MSH,

[D-Phe⁷, D-Val¹³]-alpha-MSH,

[D-Ser¹, Nle⁴, D-Phe⁷]-alpha-MSH,

[D-Tyr², Nle⁴, D-Phe⁷]-alpha-MSH,

[D-Ser³, Nle⁴, D-Phe⁷]-alpha-MSH,

[Nle⁴, D-Glu⁵, D-Phe⁷]-alpha-MSH,

[Nle⁴, D-His⁶, D-Phe⁷]-alpha-MSH,

[Nle⁴, D-Phe⁷, D-Arg⁸]-alpha-MSH,

[Nle⁴, D-Phe⁷, D-Trp⁹]-alpha-MSH,

[Nle⁴, D-Phe⁷, D-Lys¹¹]-alpha-MSH,

[Nle⁴, D-Phe⁷, D-Pro¹²]-alpha-MSH,

[Nle⁴, D-Phe⁷, D-Val¹³]-alpha-MSH,

[Nle⁴, D-Phe⁷]-alpha-MSH₄₋₁₀,

[Nle⁴, D-Phe⁷]-alpha-MSH₄₋₁₁,

[D-Phe⁷]-alpha-MSH₅₋₁₁,

[Nle⁴, D-Tyr⁷]-alpha-MSH₄₋₁₁,

[(pNO₂)D-Phe⁷]-alpha-MSH₄₋₁₁,

[Tyr⁴, D-Phe⁷]-alpha-MSH₄₋₁₀,

[Tyr⁴, D-Phe⁷]-alpha-MSH₄₋₁₁,

[Nle⁴]-alpha-MSH₄₋₁₁,

[Nle⁴, (pNO₂)D-Phe⁷]-alpha-MSH₄₋₁₁,

[Nle⁴, D-His⁶]-alpha-MSH₄₋₁₁,

[Nle⁴, D-His⁶, D-Phe⁷]-alpha-MSH₄₋₁₁,

[Nle⁴, D-Arg⁸]-alpha-MSH₄₋₁₁,

[Nle⁴, D-Trp⁹]-alpha-MSH₄₋₁₁,

[Nle⁴, D-Phe⁷, D-Trp⁹]alpha-MSH₄₋₁₁,

[Nle⁴, D-Phe⁷]-alpha-MSH₄₋₉, or

[Nle⁴, D-Phe⁷, D-Trp⁹]-alpha-MSH₄₋₉.

In one aspect, the alpha-MSH analogue is

[Nle⁴, D-Phe⁷]-alpha-MSH₄₋₁₀,

[Nle⁴, D-Phe⁷]-alpha-MSH₄₋₁₁,

[Nle⁴, D-Phe⁷, D-Trp⁹]-alpha-MSH₄₋₁₁, or

[Nle⁴, D-Phe⁷]-alpha-MSH₄₋₉.

In a further aspect, the alpha-MSH analogue is [Nle⁴, D-Phe⁷]-alpha-MSH.

It will be appreciated that the actual preferred amounts of thealpha-MSH analogue in a specified case will vary according to thespecific compounds being utilized, the particular compositionsformulated, the mode of application, and the particular situs andsubject being treated. Dosages for a given host can be determined usingconventional considerations, e.g., by customary comparison of thedifferential activities of the subject compounds and of a known agent,e.g., by means of an appropriate conventional pharmacological protocol.Physicians and formulators, skilled in the art of determining doses ofpharmaceutical compounds, will have no problems determining doses forinducing melanogenesis by the methods described herein. In one aspect,the alpha-MSH analogue is administered in an amount to inducemelanogenesis without inducing homologous desensitization of themelanocortin-1 receptors of the subject. In another aspect, thealpha-MSH analogue is administered at a level not exceeding 10 ng/ml inthe plasma of the subject for a period of at least 24 hours. In variousother aspects, the alpha-MSH analogue is administered at a level notexceeding 9 ng/ml, 8 ng/ml, 7 ng/ml, 6 ng/ml, 5 ng/ml, 4 ng/ml, 3 ng/ml,2 ng/ml, 1 ng/ml, 0.5 ng/ml, 0.2 ng/ml or 0.1 ng/ml, or lower, in theplasma of the subject for a period of at least 24 hours.

Any of the alpha-MSH analogues useful herein can be administered to asubject using a variety of administration or delivery techniques knownin the art. It is desirable to maintain low concentrations of thealpha-MSH analogue in the plasma of the subject to induce melanogenesisin the subject. Therefore, the mode of administration will depend uponthe subject to be treated and the alpha-MSH analogue selected. Invarious aspects, the alpha-MSH analogues can be administered orally orparenterally. The term “oral” is used herein to encompass administrationof the compounds via the digestive tract. The term “parenteral” is usedherein to encompass any route of administration, other than oraladministration, by which the alpha-MSH analogue is introduced into thesystemic circulation which includes, but is not limited to, intravenous,intramuscular, subcutaneous, intraperitoneal, intradermal, ocular,inhalable, rectal, vaginal, transdermal, topical, buccal, sublingual, ormucosal administration. The term “mucosal” as used herein encompassesthe administration of the compounds by methods that employ the mucosa(mucous membranes) of the human body such as, but not limited to,buccal, intranasal, gingival, vaginal, sublingual, pulmonary, or rectaltissue. The term “transdermal” as used herein encompasses theadministration of the compounds that go into the skin or go through theskin using formulations such as, but not limited to, transdermalformulations, buccal patches, skin patches, or transdermal patches. Theterm “topical” as used herein encompasses administration by applyingconventional topical preparations such as creams, gels, or solutions forlocalized percutaneous delivery and/or by solution for systemic and/orlocalized delivery to areas such as, but not limited to the eye, skin,rectum, and vagina.

In one aspect, delivery systems composed of devices or compositionscontaining an alpha-MSH analogue can be manufactured that allow for thecontrolled-release, extended-release, modified-release,sustained-release, pulsatile-release, or programmed-release delivery ofthe alpha-MSH analogue in order to maintain low concentrations of thealpha-MSH analogue in the plasma of the subject. Depending on thedelivery system or composition of a formulation or route ofadministration chosen, drugs or active pharmaceutical ingredients can bedelivered for hours, weeks, or months following a single administration.Drug-delivery devices include, but are not limited to pumps, needle-freeinjectors, metered-dose inhalers, and the like. Transdermal compositionswith or without penetration enhancers include but are not limited totransdermal patches, microneedles, and transdermal formulations thatachieve drug delivery using inotophoresis, sonophoresis,electroporation, thermoporation, perfusion, adsorption and absorption.Other delivery systems include, but are not limited to, biodegradable ornon-biodegradable rods or other shaped implants, fibers, microparticles,microspheres, microcapsules, nanospheres, nanocapsules, porous siliconnanoparticles, in situ gelling formulations, in situ bolus formingcompositions, quick dissolving tablets and the like, buccal patches,films, tablets, capsules, osmotic pressure driven formulations, liquidfilled capsules, liposomes and other lipid based compositions and thelike, pegalation and the like, hydrogel formulations, emulsions,microemulsions, and suspensions.

In one aspect, polymeric delivery systems can be microparticlesincluding, but not limited to microspheres, microcapsules, nanospheresand nanoparticles comprising biodegradable polymeric excipients,non-biodegradable polymeric excipients, or mixtures of polymericexcipients thereof, or the polymeric delivery systems can be, but notlimited to rods or other various shaped implants, wafers, fibers, films,in situ forming boluses and the like comprising biodegradable polymericexcipients, non-biodegradable polymeric excipients, or mixtures thereof.These systems can be made from a single polymeric excipient or a mixtureor blend of two or more polymeric excipients.

A suitable polymeric excipient includes, but is not limited to, apoly(diene) such as poly(butadiene) and the like; a poly(alkene) such aspolyethylene, polypropylene, and the like; a poly(acrylic) such aspoly(acrylic acid) and the like; a poly(methacrylic) such as poly(methylmethacrylate), a poly(hydroxyethyl methacrylate), and the like; apoly(vinyl ether); a poly(vinyl alcohol); a poly(vinyl ketone); apoly(vinyl halide) such as poly(vinyl chloride) and the like; apoly(vinyl nitrile), a poly(vinyl ester) such as poly(vinyl acetate) andthe like; a poly(vinyl pyridine) such as poly(2-vinyl pyridine),poly(5-methyl-2-vinyl pyridine) and the like; a poly(styrene); apoly(carbonate); a poly(ester); a poly(orthoester) including acopolymer; a poly(esteramide); a poly(anhydride); a poly(urethane); apoly(amide); a cellulose ether such as methyl cellulose, hydroxyethylcellulose, hydroxypropyl methyl cellulose, and the like; a celluloseester such as cellulose acetate, cellulose acetate phthalate, celluloseacetate butyrate, and the like; a poly(saccharide), a protein, gelatin,starch, gum, a resin, and the like. These materials may be used alone,as physical mixtures (blends), or as co-polymers. Derivatives of any ofthe polymers listed above are also contemplated.

In one aspect, the polymeric excipient of the delivery system includes abiocompatible, non-biodegradable polymer such as, for example, asilicone, a polyacrylate; a polymer of ethylene-vinyl acetate; an acylsubstituted cellulose acetate; a non-degradable polyurethane; apolystyrene; a polyvinyl chloride; a polyvinyl fluoride; a poly(vinylimidazole); a chlorosulphonate polyolefin; a polyethylene oxide; or ablend or copolymer thereof.

In another aspect, the polymeric excipient includes a biocompatible,biodegradable polymer such as, for example, a poly(lactide); apoly(glycolide); a poly(lactide-co-glycolide); a poly(lactic acid); apoly(glycolic acid); a poly(lactic acid-co-glycolic acid); apoly(caprolactone); a poly(orthoester); a poly(phosphazene); apoly(hydroxybutyrate) or a copolymer containing a poly(hydroxybutarate);a poly(lactide-co-caprolactone); a polycarbonate; a polyesteramide; apolyanhydride; a poly(dioxanone); a poly(alkylene alkylate); a copolymerof polyethylene glycol and a polyorthoester; a biodegradablepolyurethane; a poly(amino acid); a polyetherester; a polyacetal; apolycyanoacrylate; a poly(oxyethylene)/poly(oxypropylene) copolymer, ora blend or copolymer thereof.

In one aspect, the delivery system comprises an implant or rod, whereinthe implant or rod comprises a biodegradable polymer, wherein thealpha-MSH analogue is imbedded within the implant or rod. In one aspect,the alpha-MSH analogue is encapsulated in an implant or rod composed ofpoly(lactide-co-glycolide), poly(lactide), poly(glycolide), or a mixturethereof. Lactide/glycolide polymers for drug-delivery formulations aretypically made by melt polymerization through the ring opening oflactide and glycolide monomers. Some polymers are available with orwithout carboxylic acid end groups. When the end group of thepoly(lactide-co-glycolide), poly(lactide), or poly(glycolide) is not acarboxylic acid, for example, an ester, then the resultant polymer isreferred to herein as blocked or capped. The unblocked polymer,conversely, has a terminal carboxylic group. In one aspect, linearlactide/glycolide polymers are used; however star polymers can be usedas well. In certain aspects, high molecular weight polymers can be usedfor medical devices, for example, to meet strength requirements. Inother aspects, low molecular weight polymers can be used fordrug-delivery and vaccine delivery products where resorption time andnot material strength is as important. The lactide portion of thepolymer has an asymmetric carbon. Commercially racemic DL-, L-, andD-polymers are available. The L-polymers are more crystalline and resorbslower than DL-polymers. In addition to copolymers comprising glycolideand DL-lactide or L-lactide, copolymers of L-lactide and DL-lactide areavailable. Additionally, homopolymers of lactide or glycolide areavailable.

In the case when the biodegradable polymer ispoly(lactide-co-glycolide), poly(lactide), or poly(glycolide), theamount of lactide and glycolide in the polymer can vary. In one aspect,the biodegradable polymer contains 0 to 100 mole %, 40 to 100 mole %, 50to 100 mole %, 60 to 100 mole %, 70 to 100 mole %, or 80 to 100 mole %lactide and from 0 to 100 mole %, 0 to 60 mole %, 10 to 40 mole %, 20 to40 mole %, or 30 to 40 mole % glycolide, wherein the amount of lactideand glycolide is 100 mole %. In one aspect, the biodegradable polymercan be poly(lactide), 85:15 poly(lactide-co-glycolide), 75:25poly(lactide-co-glycolide), or 65:35 poly(lactide-co-glycolide) wherethe ratios are mole ratios.

In one aspect, when the biodegradable polymer ispoly(lactide-co-glycolide), poly(lactide), or poly(glycolide), thepolymer has an intrinsic viscosity of from 0.15 to 1.5 dL/g, 0.25 to 1.5dL/g, 0.25 to 1.0 dL/g, 0.25 to 0.8 dL/g, 0.25 to 0.6 dL/g, or 0.25 to0.4 dL/g as measured in chloroform at a concentration of 0.5 g/dL at 30°C.

The amount of alpha-MSH analogue that is encapsulated or incorporated inthe biodegradable polymer will vary depending upon the selection of thebiodegradable polymer, the encapsulation or incorporation technique, andthe amount of alpha-MSH to be delivered to the subject. In one aspect,the amount of alpha-MSH analogue encapsulated in the microcapsule,implant, or rod can be up to 50% by weight of the delivery system. Inother aspects, the amount of alpha-MSH analogue encapsulated in themicrocapsule, implant, or rod can be from 5 to 60, 10 to 50%, 15 to 40%,or 15 to 30% by weight of the delivery system.

In another aspect, where the alpha-MSH analogue is delivered by anotherdelivery system such as a transdermal formulation, the amount ofalpha-MSH analogue in the formulation can be from 0.001 to 10%, or 0.05to 5% by weight of the formulation.

Other pharmaceutically-acceptable components can be encapsulated orincorporated in the delivery system in combination with the alpha-MSHanalogue. For example, the pharmaceutically-acceptable component caninclude, but is not limited to, a fatty acid, a sugar, a salt, awater-soluble polymer such as polyethylene glycol, a protein,polysaccharide, or carboxmethyl cellulose, a surfactant, a plasticizer,a high- or low-molecular-weight porosigen such as polymer or a salt orsugar, or a hydrophobic low-molecular-weight compound such ascholesterol or a wax. In another aspect, the delivery system comprisesan implant or rod, wherein the alpha-MSH analogue is [Nle⁴,D-Phe⁷]-alpha-MSH in the amount from 15% to 45% by weight of the implantor rod, wherein the rod or implant comprises poly(lactide) orpoly(lactide-co-glycolide) such as, for example, 85:15poly(lactide-co-glycolide).

Any of the delivery systems described herein can be administered usingtechniques known in the art. In one aspect, the delivery system can beadministered subcutaneously to the subject. In this aspect, the durationof administration can vary depending upon the amount of alpha-MSHanalogue that is encapsulated and the biodegradable polymer selected. Inone aspect, the delivery system is administered subcutaneously to thesubject and releases the alpha-MSH analogue for a period of at least 1,2, 4, 6, 8, 10 or 12 days. In one aspect, the delivery system releasesthe alpha-MSH analogue in the subject for up to three months. In variousother aspects, the delivery system releases the alpha-MSH analogue inthe subject for 5 days, 10 days, 15 days, 20 days, 25 days, or 30 days.

In one aspect, any of the alpha-MSH analogues can be combined with atleast one pharmaceutically-acceptable carrier to produce apharmaceutical composition. The pharmaceutical compositions can beprepared using techniques known in the art. In one aspect, thecomposition is prepared by admixing the alpha-MSH analogue with apharmaceutically-acceptable carrier. The term “admixing” is defined asmixing the two components together so that there is no chemical reactionor physical interaction. The term “admixing” also includes the chemicalreaction or physical interaction between the alpha-MSH analogue and thepharmaceutically-acceptable carrier.

Pharmaceutically-acceptable carriers are known to those skilled in theart. These most typically would be standard carriers for administrationto humans, including solutions such as sterile water, saline, andbuffered solutions at physiological pH.

Molecules intended for pharmaceutical delivery may be formulated in apharmaceutical composition. Pharmaceutical compositions may includecarriers, thickeners, diluents, buffers, preservatives, surface activeagents and the like in addition to the molecule of choice.Pharmaceutical compositions may also include one or more activeingredients such as antimicrobial agents, antiinflammatory agents,anesthetics, and the like.

Preparations for administration include sterile aqueous or non-aqueoussolutions, suspensions, and emulsions. Examples of non-aqueous carriersinclude water, alcoholic/aqueous solutions, emulsions or suspensions,including saline and buffered media. Parenteral vehicles, if needed forcollateral use of the disclosed compositions and methods, include sodiumchloride solution, Ringer's dextrose, dextrose and sodium chloride,lactated Ringer's, or fixed oils. Intravenous vehicles, if needed forcollateral use of the disclosed compositions and methods, include fluidand nutrient replenishers, electrolyte replenishers (such as those basedon Ringer's dextrose), and the like. Preservatives and other additivesmay also be present such as, for example, antimicrobials, anti-oxidants,chelating agents, and inert gases and the like.

Formulations for topical administration may include ointments, lotions,creams, gels, drops, ointments, suppositories, sprays, liquids andpowders. Conventional pharmaceutical carriers, aqueous, powder or oilybases, thickeners and the like may be necessary or desirable. Thealpha-MSH analogue can be admixed under sterile conditions with aphysiologically acceptable carrier and any preservatives, buffers,propellants, or absorption enhancers as may be required or desired.Reference is made to documents cited herein, e.g., U.S. Pat. No.5,990,091, WO 98/00166, and WO 99/60164, for the preparation ofcompositions for topical applications, e.g., viscous compositions thatcan be creams or ointments, as well as compositions for nasal andmucosal administration.

In the case when the composition is administered mucosally, ocularly,intranasally, or by inhalation, the formulation can be in the form of adrop, a spray, an aerosol, or a sustained release format. The spray andthe aerosol can be achieved through use of the appropriate dispenser.The sustained release format can be an ocular insert, erodiblemicroparticulates, swelling mucoadhesive particulates, pH sensitivemicroparticulates, nanoparticles/latex systems, ion-exchange resins andother polymeric gels and implants (Ocusert, Alza Corp., California;Joshi, A., S. Ping and K. J. Himmelstein, Patent Application WO91/19481). These systems maintain prolonged drug contact with theabsorptive surface preventing washout and nonproductive drug loss.

The methods described herein induce melanogenesis in a subject (i.e,increase melanin production from melanin-producing cells). The methodsherein increase melanin production without inducing homologousdesensitization of the melanocortin-1-receptors of the subject. Bymaintaining low concentrations of the alpha-MSH analogue in the plasmaof the subject, it is possible to increase melanin production withoutinducing homologous desensitization of the melanocortin-1-receptors ofthe subject, which can prevent the occurrence of skin damage in asubject due to exposure to UV radiation. In one aspect, described hereinare methods for preventing UV radiation-induced skin damage in a humansubject comprising administering to the subject an alpha-MSH analogue,wherein the alpha-MSH analogue is administered at a level to inducemelanogenesis in the subject without inducing homologous desensitizationof the melanocortin-1-receptors of the subject. In another aspect,described herein are methods for preventing UV radiation-induced skindamage in a human subject comprising administering to the subject analpha-MSH analogue, wherein the alpha-MSH analogue is administered at alevel not exceeding 10 ng/ml in the plasma of the subject for a periodof at least 24 hours.

In yet another aspect, described herein are compositions for preventingUV radiation-induced skin damage in a human subject, wherein thecomposition administers an alpha-MSH analogue to the subject in aneffective amount and time to induce melanogenesis by the melanocytes inepidermal tissue of the subject without inducing homologousdesensitization of the melanocortin-1 receptors of the subject. In afurther aspect, described herein are compositions for preventing UVradiation-induced skin damage in a human subject, wherein thecomposition administers an alpha-MSH analogue to the subject at a levelnot exceeding 10 ng/ml in the plasma of the subject for a period of atleast 24 hours.

In one aspect, an epidermal cell can be contacted with the alpha-MSHanalogue in order to prevent UV radiation-induced skin damage in asubject. In these aspects, the epidermal cell can be contacted with thealpha-MSH analogue in vivo, in vitro, or ex vivo

EXAMPLES

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how thecompounds, compositions, and methods described and claimed herein aremade and evaluated, and are intended to be purely exemplary and are notintended to limit the scope of what the inventors regard as theirinvention. Efforts have been made to ensure accuracy with respect tonumbers (e.g., amounts, temperature, etc.) but some errors anddeviations should be accounted for. Unless indicated otherwise, partsare parts by weight, temperature is in ° C. or is at ambienttemperature, and pressure is at or near atmospheric. There are numerousvariations and combinations of reaction conditions, e.g., componentconcentrations, component mixtures, desired solvents, solvent mixtures,temperatures, pressures and other reaction ranges and conditions thatcan be used to optimize the product purity and yield obtained from thedescribed process. Only reasonable and routine experimentation will berequired to optimize such process conditions.

I. PREPARATION OF FORMULATIONS Example 1 Fabrication of ImplantsContaining 20 Mg of Melanotan

[Nle⁴-D-Phe⁷]-α-MSH, (Melanotan; MT-1), is the medication involved inthe studies described below. The substitution of amino acids atpositions 4 and 7 makes this analogue 10-1000 times more active thanα-MSH in one or more bioassays.⁷ An implant formulation was made forStudy 3 with Melanotan and poly(DL-lactide). The poly(DL-lactide) had aninherent viscosity of 0.37 dL/g. The inherent viscosity was measured at30° C. with 0.5 gm/dL polymer concentration in chloroform.

The desired Melanotan content in the implant was 35 wt % Melanotanpeptide. Therefore, Melanotan (36 g, where 78% is Melanotan peptide) andthe poly(DL-lactide) (44 g) were dry blended using a mortar and pestleto form a blended powder.

Next a Tinius Olsen (MP 600) melt plastometer was used to melt extrudethe blended powder. The Tinius Olsen is a solid block of steel about 80mm in diameter and about 160 mm high/long with a hollow core about 13 mmin diameter. The discharge of the core has a shoulder that allowsdifferent size “dies” to be used based on the desired diameter ofextruded rod. For this run, a 3.9-mm die was used, meaning that the coreof the die was 3.9 mm in diameter. The main block of the Tinius Olsenhas heater bands encased by insulation and a shroud that allow theTinius Olsen to be heated to a desired temperature. A thermocouple wasused to measure the temperature of the block. The control system thenuses the thermocouple values to either turn the heater bands on or off.Throughout the extrusion process, the heater bands will switch off andon to maintain the desired temperature. Once the blend was loaded intothe Tinius Olsen, a charging rod was placed in the core or the TiniusOlsen to compress the blend. Weights were placed on the end of thecharging rod as appropriate. More specifically, the Tinius Olsen wasequilibrated to 90° C. The compression load used, while the blend wasmelting, was 3,700 grams. The equilibration time for the blend to meltlasted for about 15 minutes. The plug was removed from the dischargearea and the extrusion load of 12,360 grams was added, which includedthe compression load. An extruded rod of approximately 140-180 cm wasthen made.

Ten 10 samples (about 55 mg each) were selected for potency testing(Melanotan content). The potency test determined that the extruded rodcontained 34.19 wt % Melanotan. Knowing the Melanotan content, theextruded rods were then cut into lengths to afford implants with about20 mg Melanotan peptide in each implant.

Next about 30 mL of ethyl acetate were placed in a small beaker. Eachimplant was affixed to a needle point holding device and dipped in theethyl acetate for about 5 seconds. The implants were then “dried” atroom conditions.

The in vitro release characteristics of similar Melanotan implants madewith poly(DL-lactide) by the above-described manufacturing process areshown in FIG. 1. The Melanotan content was 36 wt %. The release datashowed that the implants released Melanotan for up to 21 days.

Example 2 Preparation of Implants with Different Lactide/GlycolidePolymers

Several Melanotan implants were made essentially by the extrusionprocess described in Example 1. However, the properties of the implantsvaried with respect to:

-   -   Lactide/glycolide ratio of the polymer    -   Polymer end group    -   Polymer inherent viscosity    -   Melanotan content        Table 1 lists representative examples of the different implants        prepared.

TABLE 1 Inherent Run Lactide/Glycolide viscosity Polymer end Melanotancontent No. (mole ratio) (dL/gm) group (wt %)  1^(a) 100:0  0.37 Capped36.0 2 100:0  0.67 Capped 29.2 3 100:0  1.09 Capped 26.9 4 85:15 0.36COOH 20.8 5 85:15 0.36 COOH 17.4 6 85:15 0.36 COOH 17.3 7 75:25 0.44Capped 15.0 8 75:25 0.44 Capped 16.9 9 65:35 0.42 Capped 16.7^(a)Solvent treated

In summary, the polymers for the above implants ranged from homopolymers(poly(DL-lactide)) to copolymers of lactide and glycolide. Therefore,polymers with 100 mole % lactide to 65 mole % lactide were used. The endgroups of these polymers were capped (blocked) or were synthesized tohave carboxylic acid end groups. The inherent viscosity of the polymersranged from 0.36 to 1.09 dL/g. The inherent viscosities were determinedwith polymers dissolved in chloroform at a concentration of 0.5 gm/dL.The viscosity measurements were made at 30° C. The Melanotan content ofthe implants ranged from 15 to 45 wt %. The typical in vitro releasecharacteristics of the Melanotan implants made with 85:15poly(DL-lactide-co-glycolide) in runs 4 and 5 are shown in FIG. 2.

Example 3 Fabrication of Implants Containing 5 Mg of Melanotan

An implant formulation was made with Melanotan and 84:16poly(DL-lactide-co-glycolide) with carboxylic acid end groups. Thepoly(DL-lactide-co-glycolide) had an inherent viscosity of 0.29 dL/g.The inherent viscosity was measured at 30° C. with 0.5 gm/dL polymerconcentration in chloroform.

The desired Melanotan content in the implant was 17.3 wt % Melanotanpeptide. Therefore, Melanotan (3 g) and the poly(DL-lactide) (12 g) weredry blended using a mortar and pestle to form a blended powder. The 3 gmof Melanotan comprised about 88% Melanotan peptide.

Next a Tinius Olsen (MP 600) melt plastometer was used to melt extrudethe blended powder. The Tinius Olsen is a solid block of steel about 80mm in diameter and about 160 mm high/long with a hollow core about 13 mmin diameter. The discharge of the core has a shoulder that allowsdifferent size “dies” to be used based on the desired diameter ofextruded rod. For this run, a 1.5-mm die was used, meaning that the coreof the die was 1.5 mm in diameter. The main block of the Tinius Olsenhas heater bands encased by insulation and a shroud that allow theTinius Olsen to be heated to a desired temperature. A thermocouple wasused to measure the temperature of the block. The control system thenused the thermocouple values to either turn the heater bands on or off.Throughout the extrusion process the heater bands will switch off and onto maintain the desired temperature. Once the blend was loaded into theTinius Olsen, a charging rod was placed in the core or the Tinius Olsento compress the blend. Weights were placed on the end of the chargingrod as appropriate. More specifically, the Tinius Olsen was equilibratedto 87° C. The compression load used, while the blend was melting, was3,700 grams. The equilibration time for the blend to melt lasted forabout 15 minutes. The plug was removed from the discharge area and theextrusion load of 10,300 grams was added (includes the compressionload). An extruded rod approximately 600-700 cm was then made.

Ten 10 samples (about 30 mg each) were selected for potency testing(Melanotan content). The potency test determined that the extruded rodcontained 16.08 wt % Melanotan. Knowing the Melanotan content, theextruded rods were then cut into lengths to afford implants with about 5mg Melanotan peptide in each implant. The in vitro releasecharacteristics of similar Melanotan implants made with 84:16poly(DL-lactide-co-glycolide)) by the above-described manufacturingprocess are shown in FIG. 3. The Melanotan content is 16 wt %. Theserelease data showed that the implants released Melanotan for at least 21days.

II. IN VIVO TESTING Example 4 Clinical Trials

Four clinical trials were conducted using different means of deliveringof Melanotan (MT-1). In the first clinical trial, a double-blind,randomized, placebo-controlled clinical trial was conducted with 16human subjects, later reduced to 15 subjects. Melanotan (MT-1) wasadministered at a fixed, subcutaneous daily dose for 10 consecutive daysto 12 subjects, and the remaining 4 subjects were administered theplacebo (saline). One subject (Melanotan) did not complete the trialprotocol. Average baseline melanin density (MD) and MD change (%) wasmeasured in all 11 protocol completers. In the second clinical trial, adouble-blind, randomized, placebo-controlled clinical trial wasconducted with 81 human subjects, later reduced to 79 subjects.Melanotan (MT-1) was administered at a fixed, subcutaneous daily dosefor 30 days over a 70 day period to 59 subjects, and the remaining 20subjects were administered the placebo (saline). Fourteen subjects didnot complete the trial protocol (twelve Melanotan and two placebo).Average baseline melanin density (MD) and MD change (%) was measured inall 47 protocol completers. In the third clinical trial, adose-escalation study of a single depot controlled release formulationwas conducted with 3 human subjects. Melanotan (MT-1) was administeredas a single, subcutaneous controlled release dose at day 1 only. Averagebaseline melanin density (MD) and MD change (%) was measured in thesethree subjects. In the fourth clinical trial, a dose-escalation study ofa single depot controlled release formulation was conducted with 12human subjects. Melanotan (MT-1) was administered as a single,subcutaneous controlled release dose at day 1 only. Average baselinemelanin density (MD) and MD change (%) was measured in these twelvesubjects.

The results of these trials show that the MD change (%) of the subjectsof Studies 3 and 4 was dramatically higher and quicker than for thesubjects of Studies 1 and 2, notwithstanding the fact that the subjectsof Studies 3 and 4 received a substantially lower amount of Melanotanoverall when compared with the subjects of Studies 1 and 2.

a. Primary Objective

Study 1:

One of the primary objectives of this study was to determine thepharmacokinetics of 0.16 mg/kg/day of Melanotan administered bysubcutaneous injection on 10 consecutive days to healthy adult subjects.

Study 2:

One of the primary objectives of this study was to compare the incidenceof sunburn cells (defined as apoptotic cells) in all subjects elicited24 hours after controlled solar irradiation (3×MED) to a small area ofskin (2×2 cm) at baseline and 90 days after initiation of dosing withMelanotan or placebo.

Studies 3 and 4:

One of the primary objectives of this study was to determine thepharmacokinetics of increasing doses of a single depot injection ofMelanotan administered subcutaneously to healthy adult subjects.

b. Secondary Objective

To establish the safety and tolerability (defined as absence of anytoxicities≧Grade 3 by WHO-CTC) of a course of Melanotan (MT-1) given aseither a course of 10 consecutive daily liquid injections at a fixedsubcutaneous dose of 0.16 mg/Kg/day in Caucasian subjects (study 1), or3 (10 day; 5 days a week×2 weeks) monthly courses of Melanotan (MT-1) ata fixed subcutaneous dose of 0.16 mg/Kg/day in Caucasian subjects (study2), or as a single depot injection of Melanotan (MT-1) in Caucasiansubjects (Studies 3 and 4).

c. Primary Efficacy Objective (for all four studies)

Degree of Tanning

To compare the degree of tanning at 8 anatomic sites (determined byserial reflectance changes) at set periods after initiation of dosingwith Melanotan and placebo in Caucasian subjects.

A. Testing Protocol 1. Selection of Study Population

The target population was male and female Caucasian subjects. Thefollowing inclusion and exclusion criterion had to be met by eachsubject before enrollment in the study. The inclusion and exclusioncriterion was similar for all three studies conducted.

Inclusion Criteria

-   -   Male and Female Caucasian Subjects (skin types I to IV on the        Fitzpatrick scale¹⁶)    -   Age 18-65 years    -   Weight≦85 Kg    -   Free of significant abnormal findings as determined by medical        history (including family history), physical examination,        haematology, plasma biochemistry and vital signs (blood        pressure, pulse rate) determined at screening    -   Written informed consent prior to the performance of any        study-specific procedures

2. Study Medication

2.1 Description of Study Medication

For Studies 1 and 2, Melanotan was provided in single-use sterile 6 mLvials each containing 16 mg/mL of Melanotan dissolved in 1 mL sterilesaline for injection. Placebo vials were identical and contained 1 mLsterile saline for injection. For Studies 3 and 4, Melanotan wasprovided in biodegradable rods.

2.2 Dosage and Administration of Study Medication

For Study 1:

Active: Melanotan was provided in single-use, sterile 6 mL vials eachcontaining 16 mg (±5%) of Melanotan in 1 mL sterile saline. A dose of0.16 mg/kg/day was administered by subcutaneous injection to eachsubject receiving the Melanotan treatment, which is equivalent to a dosevolume of 0.01 mL/kg/day.

Placebo: Placebo was provided as single-use, sterile 6 mL vialscontaining 1 mL sterile saline. A dose volume of 0.01 mL/kg/day wassubcutaneously injected at each administration.

The treatments were injected subcutaneously, using a 25-gauge needle (16mm length) and 1 mL syringe, to the abdomen each day for 10 consecutivedays. Each subject's body weight was determined at check-in and the sameweight was used for all dose calculations for subsequent treatments.Each subject received, in total, 1.6 mg/kg of Melanotan, which equatesto 112 mg of Melanotan for a 70 kg person.

For Study 2:

Active: Melanotan was provided in single-use, sterile 6 mL vials eachcontaining 16 mg (±5%) of Melanotan in 1 mL sterile saline. A dose of0.16 mg/kg/day was administered by subcutaneous injection to eachsubject receiving the Melanotan treatment, which is equivalent to a dosevolume of 0.01 mL/kg/day.

Placebo: Placebo was provided as single-use, sterile 6 mL vialscontaining 1 mL sterile saline. A dose volume of 0.01 mL/kg/day wassubcutaneously injected at each administration.

The treatments were injected subcutaneously, using a 25 gauge needle (16mm length) and 1 mL syringe, to the abdomen each day for 5 days a week×2weeks. Each subject's body weight was determined at check-in and thesame weight was used for all dose calculations for the first 10 daystreatment. This cycle of treatment was repeated at Days 29 to 40 andDays 57 to 66. The subject was reweighed at the start of each dosingperiod for calculation of dose. Drug was given as nearly as possible atthe same time each day (+/−4 hours). Each subject received, in total,4.8 mg/kg of Melanotan, which equates to 336 mg of Melanotan for a 70 kgperson.

For Study 3:

Active: Melanotan was provided in a biodegradable poly(DL-lactide) rodcontaining 20 mg (±10%) of Melanotan. A single dose of 20 mg wasadministered by subcutaneous implantation to each subject.

The treatments were implanted subcutaneously, using a trocar deliverydevice (5.2 mm ID×70 mm length), in the abdomen on Day 1 only. Eachsubject received, in total, 0.29 mg/kg of Melanotan, which equates to 20mg of Melanotan for a 70 kg person.

For Study 4:

Active: Melanotan was provided in a biodegradablepoly(DL-lactide-co-glycolide) rod containing 5 mg (±10%) of Melanotan.Doses of 10 and 20 mg were administered by subcutaneous implantation toeach subject.

The treatments were implanted subcutaneously, using a SURFLO® I.V.catheter with a 16G needle, in the inner upper arm on Day 1 only.

2.3 Use of sunscreen products:

All subjects were advised to apply SPF 25+ sunscreen to exposed skinwhenever they expected to be in the sun for prolonged periods of time.Normal daily activity did not require extra precautions.

3. Study Procedures

3.1 Measurement of Primary Objective

For Study 1:

Blood collection was performed at 0 hr (time of treatment) and 0.5, 1,2, 3, 4, 6, 8, 10, 16 and 24 hr post-treatment on Day 1 and Day 10 ofthe study for pharmacokinetic analysis after dose administration.Subject plasma samples were analysed for Melanotan using a validatedLC/MS/MS method.

For Study 2:

On Day −7 to −2, subjects had their MED (minimal erythema dose)determined, received controlled UV radiation at 3.0 times their MED, andskin blister biopsy specimens were collected the following day. On Day89, subjects received controlled UV radiation at 3.0 times their MED,and skin blister biopsy specimens were collected the following day.Change in the number of sunburn (apoptotic) cells/100 cells, ofepidermis resulting from 3×MED exposure from the beginning to the end ofthe study period as determined by light microscopy, was calculated.

For Study 3:

Blood collection was performed at Day 0 (time of treatment) and Day 2,4, 6, 8, 10, 12, 15, 18, 21 and 25 post-implantation for pharmacokineticanalysis after dose administration. Subject plasma samples were analysedfor Melanotan using a validated LC/MS/MS method.

For Study 4:

Blood collection was performed at Day 0 (time of treatment) and Day 1,2, 3, 4, 6, 8, 10, 12, 15, 20 and 25 post-implantation forpharmacokinetic analysis after dose administration. Subject plasmasamples were analysed for Melanotan using a validated LC/MS/MS method.

3.2 Measurement of Primary Efficacy Variables

Skin Reflectance—Degree of Tanning & Melanin Density (MD) For Study 1:

Before treatment (Day 0), Day 9 and at Day 30, subjects had their skinpigmentation measured by a non-invasive quantitative skin chromaticity(reflectance) reading. Reflectance by the skin of wavebands of lightmeasured at 20-nm intervals in the wavelength range 400-700 nm wasrecorded using a Minolta 508i spectrophotometer at eight skin sites(forehead, cheeks, neck, scapula, inner upper arm, forearm, abdomen andcalf). The spectrophotometer was programmed to take three separatemeasurements at each site at each session to minimize error. A diagramfor each subject was provided at baseline and measurements positions forall eight skin sites at baseline were recorded on this diagram.Subsequent repeat measurements were done with reference to the initialdiagram to ensure they were taken as close as possible to the originalmeasurement at each skin site.

At each visit the mean of the 3 separate measurements taken at each sitefor the reflectance values at 400 and 420 nm were obtained and recorded.Using the measurement of reflectance at 420 nm minus that at 400 nm areasonable prediction of the melanin content of the skin was obtained,as described by Dwyer et al.²⁸

The equation used was MD=100×(0.035307+0.009974(R ₄₂₀ −R ₄₀₀))

where MD is an estimate of the percentage of the epidermis of the skinthat contains melanin, R₄₀₀ and R₄₂₀ denote reflectance at 400 nm and420 nm, respectively. These MD measurements were calculated at theanalysis stage.

For Study 2:

Before treatment (Day 0), Day 12, Day 30, Day 40, Day 60 and Day 90,subjects had their skin pigmentation measured by a non-invasivequantitative skin chromaticity (reflectance) reading. Reflectance by theskin of wavebands of light measured at 20-nm intervals in the wavelengthrange 400-700 nm was recorded using a Minolta 508i spectrophotometer ateight skin sites (forehead, cheeks, neck, scapula, inner upper arm,forearm, abdomen and calf). The spectrophotometer was programmed to takethree separate measurements at each site at each session to minimizeerror. A diagram for each subject was provided at baseline andmeasurements positions for all eight skin sites at baseline wererecorded on this diagram. Subsequent repeat measurements were done withreference to the initial diagram to ensure they were taken as close aspossible to the original measurement at each skin site.

At each visit the mean of the 3 separate measurements taken at each sitefor the reflectance values at 400 and 420 nm were obtained and recorded.Using the measurement of reflectance at 420 nm minus that at 400 nm areasonable prediction of the melanin content of the skin was obtained,as described by Dwyer et al.²⁸

The equation used was MD=100×(0.035307+0.009974(R ₄₂₀ −R ₄₀₀))

where MD is an estimate of the percentage of the epidermis of the skinthat contains melanin, R₄₀₀ and R₄₂₀ denote reflectance at 400 nm and420 nm, respectively. These MD measurements were calculated at theanalysis stage.

For Study 3:

Before treatment (Day 0), Day 10, Day 21, Day 30 and Day 60, subjectshad their skin pigmentation measured by a non-invasive quantitative skinchromaticity (reflectance) reading. Reflectance by the skin of wavebandsof light measured at 20-nm intervals in the wavelength range 400-700 nmwas recorded using a Minolta 508i spectrophotometer at eight skin sites(forehead, cheeks, neck, scapula, inner upper arm, forearm, abdomen andcalf). The spectrophotometer was programmed to take three separatemeasurements at each site at each session to minimize error. A diagramfor each subject was provided at baseline and measurements positions forall eight skin sites at baseline were recorded on this diagram.Subsequent repeat measurements were done with reference to the initialdiagram to ensure they were taken as close as possible to the originalmeasurement at each skin site.

At each visit the mean of the 3 separate measurements taken at each sitefor the reflectance values at 400 and 420 nm were obtained and recorded.Using the measurement of reflectance at 420 nm minus that at 400 nm areasonable prediction of the melanin content of the skin was obtained,as described by Dwyer et al.²⁸

The equation used was MD=100×(0.035307+0.009974(R ₄₂₀ −R ₄₀₀))

where MD is an estimate of the percentage of the epidermis of the skinthat contains melanin, R₄₀₀ and R₄₂₀ denote reflectance at 400 nm and420 nm, respectively. These MD measurements were calculated at theanalysis stage.

For Study 4:

Before treatment (Day 0), Day 4, Day 10, Day 20, Day 30 and Day 60,subjects had their skin pigmentation measured by a non-invasivequantitative skin chromaticity (reflectance) reading. Reflectance by theskin of wavebands of light measured at 20-nm intervals in the wavelengthrange 400-700 nm was recorded using a Minolta 508i spectrophotometer ateight skin sites (forehead, cheeks, neck, scapula, inner upper arm,forearm, abdomen and calf). The spectrophotometer was programmed to takethree separate measurements at each site at each session to minimizeerror. A diagram for each subject was provided at baseline andmeasurements positions for all eight skin sites at baseline wererecorded on this diagram. Subsequent repeat measurements were done withreference to the initial diagram to ensure they were taken as close aspossible to the original measurement at each skin site.

At each visit the mean of the 3 separate measurements taken at each sitefor the reflectance values at 400 and 420 nm were obtained and recorded.Using the measurement of reflectance at 420 nm minus that at 400 nm areasonable prediction of the melanin content of the skin was obtained,as described by Dwyer et al.²⁸

The equation used was MD=100×(0.035307+0.009974(R ₄₂₀ −R ₄₀₀))

where MD is an estimate of the percentage of the epidermis of the skinthat contains melanin, R₄₀₀ and R₄₂₀ denote reflectance at 400 nm and420 nm, respectively. These MD measurements were calculated at theanalysis stage.

4. Data Analysis

4.1 Efficacy Assessment

Primary Efficacy Objective For Study 1:

Change in tanning from baseline (Day 0) to day 30, across 8 anatomicsites (forehead, cheeks, neck, scapula, inner upper arm, forearm,abdomen and calf), as determined by melanin density (MD) from skinreflectance measurements [Dwyer et al.²⁸; MD=100×(0.035307+0.009974(R₄₂₀−R₄₀₀)] was calculated.

For Study 2:

Change in tanning from baseline (Day 0) to day 90, across 8 anatomicsites (forehead, cheeks, neck, scapula, inner upper arm, forearm,abdomen and calf), as determined by melanin density (MD) from skinreflectance measurements [Dwyer et al.²⁸; MD=100×(0.035307+0.009974(R₄₂₀−R₄₀₀)] was calculated.

For Studies 3 and 4:

Change in tanning from baseline (Day 0) to day 60, across 8 anatomicsites (forehead, cheeks, neck, scapula, inner upper arm, forearm,abdomen and calf), as determined by melanin density (MD) from skinreflectance measurements [Dwyer et al.²⁸; MD=100×(0.035307+0.009974(R₄₂₀−R₄₀₀)] was calculated.

B. Results

The following Tables 2, 3 and 4 list the responses of the protocolcompleters in Studies 1, 3 and 4 respectively in terms of the measuredconcentration of Melanotan in their plasma.

TABLE 2 Melanotan Plasma Concentrations (ng/mL) at Day 1 and 10 forStudy 1. Time (hr:min) post-treatment 0:00 0:30 1:00 2:00 3:00 4:00 6:008:00 10:00 16:00 24:00 Day 1 0 105 41.4 9.64 2.07 0.76 0 0 0 0 0 Day 100 100 48.1 11.3 2.9 0.28 0 0 0 0 0 Mean 0 103 44.8 10.5 2.5 0.52 0 0 0 00

TABLE 3 Melanotan Plasma Concentrations (ng/mL) for Study 3 Time (Day)post-treatment 0 2 4 6 8 10 12 15 18 21 25 0 1.39 0.41 0.17 0.12 0.060.15 0.03 0 0.01 0

TABLE 4 Melanotan Plasma Concentrations (ng/mL) for Study 4 Dose Time(Day) post-treatment (mg) 0 1 2 3 4 6 8 10 12 15 20 10 0 0.21 0.04 0.050.03 0.00 0.01 0.01 0.01 0.02 0.01 20 0 0.58 0.21 0.11 0.08 0.04 0.040.04 0.05 0.04 0.04

Based upon the data in Tables 2, 3 and 4, FIGS. 4, 5 and 6 reveal thatthe peak levels of Melanotan in the plasma of subjects that received aliquid injection was approximately 100 times greater than levels ofMelanotan in the plasma of the subjects that had received the controlledrelease dose of Melanotan.

The following Tables 5, 6, 7 and 8 list the responses of the subjectsfor each of the studies following the different dosing regimes ofMelanotan in terms of the change in melanin density (MD) measured at theinner upper arm after 30, 90 and 60 days for Studies 1, 2, 3 and 4respectively. The inner upper arm generally denotes a person'sconstitutive skin melanin since environmental exposure appears to beleast in this area.

TABLE 5 Melanin Density Change from Baseline (Inner Upper Arm) for Study1 Day 9 Day 30 0.51 ± 0.55 0.48 ± 0.53

TABLE 6 Melanin Density Change from Baseline (Inner Upper Arm) for Study2 Day 12 Day 30 Day 40 Day 60 0.28 ± 0.45 0.39 ± 0.49 0.61 ± 0.58 0.61 ±0.66

TABLE 7 Melanin Density Change from Baseline (Inner Upper Arm) for Study3 Day 10 Day 21 Day 30 Day 60 1.31 ± 0.86 1.54 ± 0.72 1.84 ± 0.74 2.18 ±0.64

TABLE 8 Melanin Density Change from Baseline (Inner Upper Arm) for Study4 Day 4 Day 10 Day 21 Day 30 Day 60 10 mg 0.417 0.465 0.638 0.677 1.34520 mg 0.300 0.791 0.946 1.384 2.114

Based on the data in Tables 5-8, FIG. 7 shows that the melanin densitychange of the subjects in Studies 3 and 4 was dramatically higher andquicker than for Studies 1 and 2. This unexpected result is to be viewedwith the fact that the subjects in both Studies 3 and 4 received no morethan a 1/15 of the dose of Melanotan overall, when compared withsubjects in Study 2.

Throughout this application, various publications are referenced. Thedisclosures of these publications in their entireties are herebyincorporated by reference into this application in order to more fullydescribe the compounds, compositions and methods described herein.

Various modifications and variations can be made to the compounds,compositions and methods described herein. Other aspects of thecompounds, compositions and methods described herein will be apparentfrom consideration of the specification and practice of the compounds,compositions and methods disclosed herein. It is intended that thespecification and examples be considered as exemplary.

REFERENCES

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1. A method for inducing melanogenesis in a human subject comprisingadministering to the subject an alpha-MSH analogue in an effectiveamount and time to induce melanogenesis by the melanocytes in epidermaltissue of the subject without inducing homologous desensitization of themelanocortin-1 receptors of the subject.
 2. A method for inducingmelanogenesis in a human subject comprising administering to the subjectan effective amount of an alpha-MSH analogue to induce melanogenesis bythe melanocytes in epidermal tissue of the subject, wherein thealpha-MSH analogue is administered at a level not exceeding 10 ng/ml inthe plasma of the subject for a period of at least 24 hours.
 3. A methodfor preventing UV radiation-induced skin damage in a human subjectcomprising administering to the subject an alpha-MSH analogue in aneffective amount and time to induce melanogenesis by the melanocytes inepidermal tissue of the subject without inducing homologousdesensitization of the melanocortin-1 receptors of the subject.
 4. Amethod for preventing UV radiation-induced skin damage in a humansubject comprising administering to the subject an alpha-MSH analogue inan effective amount and time, wherein the alpha-MSH analogue isadministered at a level not exceeding 10 ng/ml in the plasma of thesubject for a period of at least 24 hours.
 5. The method as claimed inclaim 1, wherein the alpha-MSH analogue is administered at a level notexceeding 5 ng/ml in the plasma of the subject for a period of at least24 hours.
 6. The method as claimed in claim 1, wherein the alpha-MSHanalogue is administered at a level not exceeding 2 ng/ml in the plasmaof the subject for a period of at least 24 hours.
 7. The method asclaimed in claim 1, wherein the alpha-MSH analogue is selected from: (a)compounds of the formula:Ac-Ser-Tyr-Ser-M-Gln-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH₂ wherein M isMet, Nle or Lys; and (b) compounds of the formula:R₁-W-X-Y-Z-R₂ wherein R₁ is Ac-Gly-, Ac-Met-Glu, Ac-Nle-Glu-, orAc-Tyr-Glu-; W is -His- or -D-His-; X is -Phe-, -D-Phe-, -Tyr-, -D-Tyr-,or -(pNO₂)D-Phe⁷-; Y is -Arg- or -D-Arg-; Z is -Trp- or -D-Trp-; and R₂is —NH₂; -Gly-NH₂; or -Gly-Lys-NH₂.
 8. The method as claimed in claim 1,wherein the alpha-MSH analogue is a cyclic analogue wherein anintramolecular interaction exists (1) between the amino acid residue atposition 4 and an amino acid residue at position 10 or 11, and/or (2)between the amino acid residue at position 5 and the amino acid residueat position 10 or
 11. 9. The method of claim 8, wherein theintramolecular interaction is a disulfide bond or other covalent bond.10. The method as claimed in claim 1, wherein the alpha-MSH analogue isselected from the group consisting of:Ac-Ser-Try-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Lys-Gly-Pro-Val-NH₂Ac-Ser-Try-Ser-Nle-Asp-His-D-Phe-Arg-Trp-Lys-Gly-Pro-Val-NH₂Ac-Nle-Glu-His-D-Phe-Arg-Trp-Lys-Gly-Pro-Val-NH₂Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-Gly-Pro-Val-NH₂Ac-Nle-Asp-His-D-Phe-Arg-Trp-Gly-NH₂Ac-Nle-Glu-His-D-Phe-Arg-Trp-Lys-NH₂Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH₂Ac-Nle-Glu-His-D-Phe-Arg-Trp-Orn-NH₂Ac-Nle-Asp-His-D-Phe-Arg-Trp-Orn-NH₂Ac-Nle-Glu-His-D-Phe-Arg-Trp-Dab-NH₂Ac-Nle-Asp-His-D-Phe-Arg-Trp-Dab-NH₂Ac-Nle-Glu-His-D-Phe-Arg-Trp-Dpr-NH₂ Ac-Nle-Glu-His-Phe-Arg-Trp-Lys-NH₂Ac-Nle-Asp-His-Phe-Arg-Trp-Lys-NH₂
 11. The method as claimed in claim 1,wherein the alpha-MSH analogue is selected from the group consisting of:


12. The method as claimed in claim 1, wherein the alpha-MSH analogue is[D-Phe⁷]-alpha-MSH, [Nle⁴, D-Phe⁷]-alpha-MSH, [D-Ser¹,D-Phe⁷]-alpha-MSH, [D-Tyr², D-Phe⁷]-alpha-MSH, [D-Ser³,D-Phe⁷]-alpha-MSH, [D-Met⁴, D-Phe⁷]-alpha-MSH, [D-Glu⁵,D-Phe⁷]-alpha-MSH, [D-His⁶, D-Phe⁷]-alpha-MSH, [D-Phe⁷,D-Arg⁸]-alpha-MSH, [D-Phe⁷, D-Trp⁹]-alpha-MSH, [D-Phe⁷,D-Lys¹¹]-alpha-MSH, [D-Phe-⁷, D-Pro¹²]-alpha-MSH, [D-Phe⁷,D-Val¹³]-alpha-MSH, [D-Ser¹, Nle⁴, D-Phe⁷]-alpha-MSH, [D-Tyr², Nle⁴,D-Phe⁷]-alpha-MSH, [D-Ser³, Nle⁴, D-Phe⁷]-alpha-MSH, [Nle⁴, D-Glu⁵,D-Phe⁷]-alpha-MSH, [Nle⁴, D-His⁶, D-Phe⁷]-alpha-MSH, [Nle⁴, D-Phe⁷,D-Arg⁸]-alpha-MSH, [Nle⁴, D-Phe⁷, D-Trp⁹]-alpha-MSH, [Nle⁴, D-Phe⁷,D-Lys¹¹]-alpha-MSH, [Nle⁴, D-Phe⁷, D-Pro¹²]-alpha-MSH, [Nle⁴, D-Phe⁷,D-Val¹³]-alpha-MSH,

[Nle⁴, D-Phe⁷]-alpha-MSH₄₋₁₀, [Nle⁴, D-Phe⁷]-alpha-MSH₄₋₁₁,[D-Phe⁷]-alpha-MSH₅₋₁₁, [Nle⁴, D-Tyr⁷]-alpha-MSH₄₋₁₁,[(pNO₂)D-Phe⁷]-alpha-MSH₄₋₁₁, [Tyr⁴, D-Phe⁷]-alpha-MSH₄₋₁₀, [Tyr⁴,D-Phe⁷]-alpha-MSH₄₋₁₁, [Nle⁴]-alpha-MSH₄₋₁₁, [Nle⁴,(pNO₂)D-Phe⁷]-alpha-MSH₄₋₁₁, [Nle⁴, D-His⁶]-alpha-MSH₄₋₁₁, [Nle⁴,D-His⁶, D-Phe⁷]-alpha-MSH₄₋₁₁, [Nle⁴, D-Arg⁸]-alpha-MSH₄₋₁₁, [Nle⁴,D-Trp⁹]-alpha-MSH₄₋₁₁, [Nle⁴, D-Phe⁷, D-Trp⁹]alpha-MSH₄₋₁₁, [Nle⁴,D-Phe⁷]-alpha-MSH₄₋₉, or [Nle⁴, D-Phe⁷, D-Trp⁹]-alpha-MSH₄₋₉.
 13. Themethod as claimed in claim 1, wherein the alpha-MSH analogue is [Nle⁴,D-Phe⁷]-alpha-MSH₄₋₁₀, [Nle⁴, D-Phe⁷]-alpha-MSH₄₋₁₁, [Nle⁴, D-Phe⁷,D-Trp⁹]-alpha-MSH₄₋₁₁, or [Nle⁴, D-Phe⁷]-alpha-MSH₄₋₉.
 14. The method asclaimed in claim 1, wherein the alpha-MSH analogue is [Nle⁴,D-Phe⁷]-alpha-MSH.
 15. The method as claimed in claim 1, wherein thealpha-MSH analogue is administered orally or parenterally.
 16. Themethod as claimed in claim 1, wherein the alpha-MSH analogue isadministered intravenously, intramuscularly, subcutaneously,intraperitoneally, intradermally, ocularly, rectally, vaginally,transdermally, topically, buccally, sublingually, mucosally, or byinhalation.
 17. The method as claimed in claim 1, wherein the alpha-MSHanalogue is administered in a delivery system.
 18. The method of claim17, wherein the delivery system comprises a fiber, a microparticle, amicrosphere, a microcapsule, a nanosphere, a nanocapsule, a poroussilicone nanoparticle, an in situ gelling formulation, an in situ bolusforming composition, a tablet, a buccal patch, a film, tablets, anosmotic driven formulation, a capsule, a liquid filled capsule, aliposome, a hydrogel formulation, an emulsion, a microemulsion, or asuspension.
 19. The method of claim 17, wherein the delivery systemcomprises a rod or implant comprising a polymer.
 20. The method of claim17, wherein the delivery system further comprises apharmaceutically-acceptable component encapsulated in the deliverysystem.
 21. The method of claim 20, wherein thepharmaceutically-acceptable component comprises a fatty acid, a sugar, asalt, a water-soluble polymer, a protein, polysaccharide, a carboxmethylcellulose, a surfactant, a plasticizer, a high- or low-molecular-weightporosigen, or a hydrophobic low-molecular-weight compound.
 22. Themethod of claim 19, wherein the polymer comprises a silicone, apoly(diene), a poly(alkene), a poly(acrylic), a poly(methacrylic),poly(vinyl ether), a poly(vinyl alcohol), a poly(vinyl ketone), apoly(vinyl halide), a poly(vinyl nitrile), a poly(vinyl ester), apoly(vinyl pyridine), poly(5-methyl-2-vinyl pyridine), a poly(styrene),a poly(carbonate), a poly(ester), a poly(orthoester), apoly(esteramide), a poly(anhydride), a poly(urethane), a poly(amide), acellulose ether, a cellulose ester, a poly(saccharide), a protein,gelatin, starch, a gum, or a resin.
 23. The method of claim 19, whereinthe polymer comprises a biodegradable polymer, a non-biodegradablepolymer, or a combination thereof.
 24. The method of claim 23, whereinthe non-biodegradable polymer comprises a polyacrylate, a polymer of anethylene-vinyl acetate, an acyl substituted cellulose acetate, anon-degradable polyurethane, a polystyrene, polyvinyl chloride,polyvinyl fluoride, poly(vinyl imidazole), a chlorosulphonatepolyolefin, polyethylene oxide, a blend thereof, or copolymer thereof.25. The method of claim 23, wherein the biodegradable polymer comprisesa poly(caprolactone), a poly(orthoester), a poly(phosphazene), apoly(hydroxybutyrate) or a copolymer containing poly(hydroxybutarate), apoly(lactide-co-caprolactone), a polycarbonate, a polyesteramide, apolyanhydride, a poly(dioxanone), a poly(alkylene alkylate), a copolymerof polyethylene glycol and polyorthoester, a biodegradable polyurethane,a poly(amino acid), a polyetherester, a polyacetal, a polycyanoacrylate,poly(oxyethylene)/poly(oxypropylene) copolymer, a blend thereof, or acopolymer thereof.
 26. The method of claim 23, wherein the biodegradablepolymer comprises a poly(lactide), a poly(glycolide), apoly(lactide-co-glycolide), a poly(lactic acid), a poly(glycolic acid),a poly(lactic acid-co-glycolic acid), or a mixture thereof.
 27. Themethod of claim 26, wherein the biodegradable polymer is blocked. 28.The method of claim 26, wherein the biodegradable polymer is unblocked.29. The method of claim 26, wherein the biodegradable polymer comprisesa polymer formed from components comprising 40 to 100 mole % lactide andfrom 0 to 60 mole % glycolide.
 30. The method of claim 26, wherein thebiodegradable polymer comprises 85:15 poly(lactide-co-glycolide). 31.The method of claim 26, wherein the biodegradable polymer comprises75:25 poly(lactide-co-glycolide).
 32. The method of claim 26, whereinthe biodegradable polymer comprises poly(lactide).
 33. The method ofclaim 26, wherein the biodegradable polymer has an intrinsic viscosityof from 0.15 to 1.5 dL/g as measured in chloroform at a concentration of0.5 g/dL at 30° C.
 34. The method of claim 26, wherein the biodegradablepolymer has an intrinsic viscosity of from 0.25 to 1.5 dL/g as measuredin chloroform at a concentration of 0.5 g/dL at 30° C.
 35. The method ofclaim 17, wherein the amount of alpha-MSH analogue in the deliverysystem is up to 50% by weight.
 36. The method of claim 17, wherein theamount of alpha-MSH analogue in the delivery system is from 5 to 60% byweight.
 37. The method of claim 17, wherein the delivery systemcomprises an implant or rod, wherein the alpha-MSH analogue is [Nle⁴,D-Phe⁷]-alpha-MSH in an amount of from 15% to 45% by weight of theimplant or rod, and wherein the rod or implant comprises poly(lactide)or poly(lactide-co-glycolide).
 38. The method of claim 37, wherein whenthe implant or rod comprises poly(lactide-co-glycolide), thepoly(lactide-co-glycolide) comprises 85:15 poly(lactide-co-glycolide).39. The method as claimed in claim 17, wherein the delivery system isadministered subcutaneously to the subject.
 40. The method as claimed inclaim 17, wherein the delivery system releases the alpha-MSH analoguefor a period of at least 2 days.
 41. The method as claimed in claim 17,wherein the delivery system releases the alpha-MSH analogue for a periodof at least 10 days.
 42. The method as claimed in claim 17, wherein thedelivery system releases the alpha-MSH analogue in the subject for atleast 20 days.
 43. The method as claimed in claim 17, wherein thedelivery system releases the alpha-MSH analogue in the subject for atleast 30 days.
 44. The method as claimed in claim 1 wherein thealpha-MSH analogue is administered in a transdermal formulation.
 45. Themethod of claim 44, wherein the amount of alpha-MSH analogue in theformulation is 0.001 to 10% by weight.
 46. The method of claim 44,wherein the amount of alpha-MSH analogue in the formulation is 0.05 to5% by weight.
 47. (canceled)
 48. (canceled)
 49. (canceled) 50.(canceled)
 51. A composition for inducing melanogenesis in a humansubject, wherein the composition administers an alpha-MSH analogue tothe subject in an effective amount and time to induce melanogenesis bythe melanocytes in epidermal tissue of the subject without inducinghomologous desensitization of the melanocortin-1 receptors of thesubject.
 52. A composition for inducing melanogenesis in a humansubject, wherein the composition administers an alpha-MSH analogue tothe subject at a level not exceeding 10 ng/ml in the plasma of thesubject for a period of at least 24 hours.
 53. A composition forpreventing UV radiation-induced skin damage in a human subject, whereinthe composition administers an alpha-MSH analogue to the subject in aneffective amount and time to induce melanogenesis by the melanocytes inepidermal tissue of the subject in an effective amount and time toinduce melanogenesis by the melanocytes in epidermal tissue of thesubject without inducing homologous desensitization of themelanocortin-1 receptors of the subject.
 54. A composition forpreventing UV radiation-induced skin damage in a human subject, whereinthe composition administers an alpha-MSH analogue to the subject at alevel not exceeding 10 ng/ml in the plasma of the subject for a periodof at least 24 hours.
 55. A composition as claimed in claim 51,comprising said alpha-MSH analogue together with one or morepharmaceutically acceptable carriers and/or diluents.
 56. A compositionas claimed in claim 55, which comprises a delivery system.
 57. Acomposition as claimed in claim 56, wherein the delivery systemcomprises a rod or implant comprising a polymer.
 58. A composition asclaimed in claim 57, wherein the polymer comprises a biodegradablepolymer, a non-biodegradable polymer, or a combination thereof.
 59. Acomposition as claimed in claim 57, wherein the delivery systemcomprises an implant or rod, where the alpha-MSH analogue is [Nle⁴,D-Phe⁷]-alpha-MSH in an amount of from 15% to 45% by weight of theimplant or rod, and wherein the rod or implant comprises poly(lactide)or poly(lactide-co-glycolide).
 60. A composition as claimed in claim 55,wherein the composition is a transdermal formulation.